What happened to the database? Migrations have been applied. The database is in a modified state — how to understand what happened and how to recover?

If after applying migrations the database is in a changed state, and you need to understand what happened and how to restore:

1. Understand what exactly changed:

   • Check migration logs (e.g., Flyway or Liquibase) — which scripts were applied.
   • Compare the current schema with the expected one (using schema comparison tools).
   • Look at tables responsible for migration versions (e.g., flyway_schema_history) to see which migrations were applied.

2. Analyze the consequences:

   • If migrations changed data structure (deleted columns, tables), data may be lost.
   • If migrations added new constraints or indexes, check if this caused errors.

3. Recovery:

   • If backups are available, restore the database from backup.
   • If migrations were erroneous, try to rollback (if supported).
   • Manually restore data if possible.
   • Fix migration scripts and reapply them in a test environment.

4. Prevention:

   • Implement migration testing processes on a test database before production.
   • Use transactions in migrations if the DBMS supports it.

Thus, first gather information about applied migrations and their effects, then decide whether to restore from backup or fix the migrations.